1. Field of the Invention
This invention relates generally to gas pressure seal arrangements and, more particularly, to an improvement in seal arrangements employing abradable, labyrinth type seals.
2. Description of the Prior Art
Labyrinth seal arrangements are used extensively in devices such as gas turbine engines to seal spaces between engine components having high relative rotational speeds. Such seal arrangements are typically disposed between rotating shafts or other rotor assemblies and fixed structures within the engines forming barriers between areas of different gas pressure although they may also be found between two components rotating relative to each other and to fixed references. In either case, the necessity of maintaining high engine efficiency by minimizing gas leakage has given rise to numerous labyrinth seal proposals including abradable seals wherein rings on one of the relatively moving components physically engage cylindrical surfaces on the other of the relatively moving components and abrade or rub away portions of the surfaces to provide rotating seals of essentially zero clearance. In addition, in some applications a bearing is disposed between the relatively moving components and in close proximity to the abradable labyrinth seal. In environments such as the latter or in labyrinth seal applications generally, a labyrinth seal arrangement according to this invention represents an improvement over other known labyrinth seal arrangements through its inclusion of means for collecting material abraded from the seal.